2015MNRAS.450L...1C

T Chamaeleontis is a young star surrounded by a transitional disc, and a plausible candidate for ongoing planet formation. Recently, a substellar companion candidate was reported within the disc gap of this star. However, its existence remains controversial, with the counter-hypothesis that light from a high-inclination disc may also be consistent with the observed data. The aim of this work is to investigate the origin of the observed closure phase signal to determine if it is best explained by a compact companion. We observed T Cha in the L' and Ks filters with sparse aperture masking, with seven data sets covering a period of 3 years. A consistent closure phase signal is recovered in all L' and Ks data sets. Data were fitted with a companion model and an inclined circumstellar disc model based on known disc parameters: both were shown to provide an adequate fit. However, the absence of expected relative motion for an orbiting body over the 3-year time baseline spanned by the observations rules out the companion model. Applying image reconstruction techniques to each data set reveals a stationary structure consistent with forward scattering from the near edge of an inclined disc.